Another thing I didn't like about the movie is that soemone seeing it would have no idea that the TV show had a Western motif.

Uhh, I think the bank heist might've tipped them off. But it's a myth that Firefly was meant to be just a "space Western." It depicted a human civilization that was a hodgepodge of cultural influences and technological levels. The frontier worlds resembled the Old West while the core worlds were sleek and futuristic, with everything in between. Part of the problem with not showing the original pilot first was that audiences didn't get to see the mix of cultural and technological levels it showed and were thus given the false impression that it was just a "space Western" -- and were also deprived of the pilot's explanation for why the frontier worlds were like that.